Deposition of semiconductor integration films

ABSTRACT

Embodiments disclosed herein include methods of depositing a metal oxo photoresist using dry deposition processes. In an embodiment, the method comprises forming a first metal oxo film on the substrate with a first vapor phase process including a first metal precursor vapor and a first oxidant vapor, and forming a second metal oxo film over the first metal oxo film with a second vapor phase process including a second metal precursor vapor and a second oxidant vapor.

BACKGROUND 1) Field

Embodiments of the present disclosure pertain to the field ofsemiconductor processing and, in particular, to methods of depositing aphotoresist layer onto a substrate using vapor phase processes.

2) Description of Related Art

Lithography has been used in the semiconductor industry for decades forcreating 2D and 3D patterns in microelectronic devices. The lithographyprocess involves spin-on deposition of a film (photoresist), irradiationof the film with a selected pattern by an energy source (exposure), andremoval (etch) of exposed (positive tone) or non-exposed (negative tone)region of the film by dissolving in a solvent. A bake will be carriedout to drive off remaining solvent.

The photoresist should be a radiation sensitive material and uponirradiation a chemical transformation occurs in the exposed part of thefilm which enables a change in solubility between exposed andnon-exposed regions. Using this solubility change, either exposed ornon-exposed regions of the photoresist is removed (etched). Now thephotoresist is developed and the pattern can be transferred to theunderlying thin film or substrate by etching. After the pattern istransferred, the residual photoresist is removed and repeating thisprocess many times can give 2D and 3D structures to be used inmicroelectronic devices.

Several properties are important in lithography processes. Suchimportant properties include sensitivity, resolution, lower line-edgeroughness (LER), etch resistance, and ability to form thinner layers.When the sensitivity is higher, the energy required to change thesolubility of the as-deposited film is lower. This enables higherefficiency in the lithographic process. Resolution and LER determine hownarrow features can be achieved by the lithographic process. Higher etchresistant materials are required for pattern transferring to form deepstructures. Higher etch resistant materials also enable thinner films.Thinner films increase the efficiency of the lithographic process.

SUMMARY

Embodiments disclosed herein include methods of forming metal oxophotoresists with vapor phase processes. In an embodiment, a method offorming a photoresist layer over a substrate comprises forming a firstmetal oxo film on the substrate with a first vapor phase processincluding a first metal precursor vapor and a first oxidant vapor, andforming a second metal oxo film over the first metal oxo film with asecond vapor phase process including a second metal precursor vapor anda second oxidant vapor.

In an additional embodiment, a method of forming a photoresist layerover a substrate in a vacuum chamber comprises providing a metalprecursor vapor into the vacuum chamber, where the metal precursor has ageneric formula MR_(x)L_(y), where M is a metal, R is a leaving group, Lis a ligand, x is between 0 and 6, and y is between 0 and 6. The methodmay further comprise providing an oxidant vapor into the vacuum chamber,where a reaction between the metal precursor vapor and the oxidant vaporresults in the formation of the photoresist layer on a surface of thesubstrate, and where the photoresist layer is a metal oxo containingmaterial.

In an additional embodiment, a method of forming a photoresist layerover a substrate in a vacuum chamber comprises initiating a depositioncycle. In an embodiment, the deposition cycle comprises providing ametal precursor vapor into the vacuum chamber, where the metal precursorhas a generic formula MR_(x)L_(y), where M is a metal, R is a leavinggroup, L is a ligand, x is between 0 and 6, and y is between 0 and 6. Inan embodiment, the metal precursor vapor absorbs to a surface over thesubstrate. The deposition cycle may further comprise purging the vacuumchamber, and providing an oxidant vapor into the vacuum chamber, where areaction between the metal precursor absorbed to the surface over thesubstrate and the oxidant vapor results in the formation of thephotoresist layer over the surface of the substrate. In an embodiment,the photoresist layer is a metal oxo containing material. In anembodiment, the deposition cycle may further comprise purging the vacuumchamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a chemical equation of the synthesis of a metal precursor usedin a vapor deposition process to form a metal oxo film, in accordancewith an embodiment of the present disclosure.

FIG. 2 is a flowchart illustrating a process for forming a photoresiston a substrate using a chemical vapor deposition (CVD) process, inaccordance with an embodiment of the present disclosure.

FIG. 3 is a flowchart illustrating a process for forming a photoresiston a substrate using an atomic layer deposition (ALD) process, inaccordance with an additional embodiment of the present disclosure.

FIG. 4 is a cross-sectional illustration of a metal oxo photoresist overa substrate, in accordance with an embodiment of the present disclosure.

FIG. 5 is a flowchart illustrating a process for forming a photoresistwith a non-uniform composition through a thickness of the photoresist,in accordance with an embodiment of the present disclosure.

FIG. 6A is a cross-sectional illustration of a metal oxo photoresistover a substrate, where the metal oxo photoresist comprises a firstlayer and a second layer with different material compositions, inaccordance with an embodiment of the present disclosure.

FIG. 6B is a cross-sectional illustration of a metal oxo photoresistover a substrate, where the metal oxo photoresist comprises a pluralityof layers that provide a compositional gradient through a thickness ofthe metal oxo photoresist, in accordance with an embodiment of thepresent disclosure.

FIG. 7 is a cross-sectional illustration of a processing tool that maybe used to implement the process in FIG. 2, FIG. 3, or FIG. 5, inaccordance with an embodiment of the present disclosure.

FIG. 8 illustrates a block diagram of an exemplary computer system, inaccordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

Methods of depositing a photoresist on a substrate using vapor phaseprocesses are described herein. In the following description, numerousspecific details are set forth, such as chemical vapor deposition (CVD)and atomic layer deposition (ALD) processes and material regimes fordepositing a photoresist, in order to provide a thorough understandingof embodiments of the present disclosure. It will be apparent to oneskilled in the art that embodiments of the present disclosure may bepracticed without these specific details. In other instances, well-knownaspects, such as integrated circuit fabrication, are not described indetail in order to not unnecessarily obscure embodiments of the presentdisclosure. Furthermore, it is to be understood that the variousembodiments shown in the Figures are illustrative representations andare not necessarily drawn to scale.

To provide context, photoresist systems used in extreme ultraviolet(EUV) lithography suffer from low efficiency. That is, existingphotoresist material systems for EUV lithography require high dosages inorder to provide the needed solubility switch that allows for developingthe photoresist material. Organic-inorganic hybrid materials (e.g.,metal oxo materials systems) have been proposed as a material system forEUV lithography due to the increased sensitivity to EUV radiation. Suchmaterial systems typically comprise a metal (e.g., Sn, Hf, Zr, etc.),oxygen, and carbon. The metal oxo molecules may sometimes be referred toas nanoparticles. Metal oxo based organic-inorganic hybrid materialshave also been shown to provide lower LER and higher resolution, whichare required characteristics for forming narrow features.

Metal oxo material systems are currently disposed over a substrate usinga wet process. The metal oxo material system is dissolved in a solventand distributed over the substrate (e.g., a wafer) using wet chemistrydeposition processes, such as a spin coating process. Wet chemistrydeposition of the photoresist suffers from several drawbacks. Onenegative aspect of wet chemistry deposition is that a large amount ofwet byproducts are generated. Wet byproducts are not desirable and thesemiconductor industry is actively working to reduce wet byproductswherever possible. Additionally, wet chemistry deposition may result innon-uniformity issues. For example, spin-on deposition may provide aphotoresist layer that has a non-uniform thickness or non-uniformdistribution of the metal oxo molecules. Additionally, it has been shownthat metal oxo photoresist material systems suffer from thicknessreduction after exposure, which is troublesome in lithographicprocesses. Furthermore, in a spin-on process, the percentage of metal inthe photoresist is fixed, and cannot be easily tuned.

Accordingly, embodiments of the present disclosure provide a vacuumdeposition process for providing a metal oxo photoresist layer. Thevacuum deposition process addresses the shortcomings of the wetdeposition process described above. Particularly, a vacuum depositionprocess provides the advantages of: 1) eliminating the generation of wetbyproducts; 2) providing a highly uniform photoresist layer; 3)resisting thickness reduction after exposure; 4) providing a mechanismto tune the percentage of metal in the photoresist; and 5) enabling theformation of a photoresist layer with a tailored non-uniform materialcomposition through a thickness of the photoresist layer.

The ability to form a tailored and non-uniform material compositionthrough the thickness of the photoresist layer generates improvedproperties of the photoresist. For example, a bottom portion of thephotoresist layer that interfaces with the underlying substrate may be amaterial composition that has a higher adhesion strength. Additionally,the bottom portion of the photoresist layer may be engineered to have alower sensitivity to the radiation. In a negative tone resist, a lowersensitivity may be useful to prevent scumming after development of thephotoresist. Scumming may refer to presence of residual photoresistmaterial that is not cleared from the pattern after development.Embodiments may also include a graded material composition through athickness of the photoresist. Grading the material composition may beused to control the exposure latitude curve of the photoresist. Thisallows for control of the developed profile of the photoresist and/orcan be used to provide optical proximity correction (OPC). OPC istypically implemented by altering the pattern in the mask. However,embodiments disclosed herein allow for OPC techniques to be implementedthrough changes to the composition of the photoresist. As such, OPCchanges may be implemented without the need to change thephotolithography mask, and is therefore a more economical solution.

Embodiments disclosed herein provide various vacuum deposition processesthat comprise the reaction of a metal precursor with an oxidant. In afirst embodiment, the vacuum deposition process may be a chemical vapordeposition (CVD) process. In a second embodiment, the vacuum depositionprocess may be an atomic layer deposition (ALD) process. The vacuumdeposition process may be a thermal process in some embodiments. Inother embodiments, the vacuum deposition process may be a plasmaenhanced (PE) deposition process (e.g., PE-CVD or PE-ALD).

In an embodiment, the vacuum deposition process relies on chemicalreactions between a metal precursor and an oxidant. The metal precursorand the oxidant are vaporized to a vacuum chamber. The metal precursorreacts with the oxidant to form a photoresist layer comprising a metaloxo on the surface of a substrate. In some embodiments, the metalprecursor and the oxidant are provided to the vacuum chamber together.In other embodiments, the metal precursor and the oxidant are providedto the vacuum chamber with alternating pulses. In an ALD or PE-ALDprocess, a purge of the vacuum chamber may be provided between pulses ofthe metal precursor and the oxidant.

In an embodiment, the metal precursor may have the general formulaMR_(x)L_(y). M is a metal center, R is a leaving group, and L is aligand. In an embodiment, x may be between 0 and 6, and y may be between0 and 6. The metal precursor may be synthesized using any chemicalreaction process. For example, a generic reaction is shown in FIG. 1. Asshown, a compound SnR_(x)X_(y) (with X being Cl or Br) may be reactedwith various ligands to form the metal precursor SnR_(x)L_(y). It is tobe appreciated that the Sn metal center may be replaced with anysuitable metal atom. In an embodiment, the L ligand is responsible forreacting with the oxidant to form the metal oxo molecule, and the Rleaving group is released during exposure (e.g., EUV exposure) duringthe patterning process. As such, the sensitivity of the photoresist maybe, at least partially, impacted by the choice of leaving group R.

Choice of the metal center M, the leaving group R, and the ligand Ldrives different material properties of the metal oxo photoresist. Forexample, changes to M, R, and L may provide different sensitivities tothe radiation, different adhesive properties, different structuralproperties (i.e., to enable high aspect ratio pattern formation),different etch selectivities, among many other properties. As such, thephotoresist may be specifically tailored to a desired purpose.Furthermore, the use of vacuum deposition processes allows for changesto one or more of M, R, and L through a thickness of the photoresist toprovide non-uniform material properties within the photoresist, as willbe described in greater detail below.

In a particular embodiment, M is Sn. However, it is to be appreciatedthat M may be any suitable metal element, such as, but not limited toSn, Hf, Zr, Co, Cr, Mn, Fe, Cu, Ni, Mo, W, Ta, Os, Re, Pd, Pt, Ti, V,In, Al, Sb, Bi, Te, As, Ge, Se, Cd, Ag, Pd, Au, Er, Yb, Pr, La, Na, orMg.

In an embodiment, the ligand L may be many different chemicalstructures. In one embodiment, the ligand L may be a pseudo halideligand. Pseudo halides may include, but are not limited to, CN, CNO,SCN, N₃, or SeCN.

In an embodiment, one suitable class of ligands L for the metalprecursor is monodentate ligands that comprise a N donor atom. Thebinding mode to the metal center M is illustrated in Molecule I. Suchmonodentate ligands may include cyclic ligands. Examples of some suchligands L are provided in Molecules II-V

In an embodiment, the ligand L may also be a bidentate or monodentateligand comprising N, O, S, or P donor atoms. Binding modes to the metalcenter for such ligands are illustrated in Molecule VI and Molecule VII.In Molecules VI and VII, X and Y may be N, O, S, or P. Examples of suchligands are illustrated in Molecules VIII-XVIII.

In an embodiment, the ligand L may also be a bidentate ligand comprisingone N donor atom and one O donor atom with the donor atoms bonded to themetal center M. The binding mode to the metal center M for such ligandsis illustrated in Molecule XIX. Examples of such ligands are illustratedin Molecules XX-XXIV.

In an embodiment, the ligand L may also comprise a N donor atom that isdonating to more than one metal center. Examples of bonding modes ofsuch ligands are illustrated in Molecules XXV-XXVII.

In an embodiment, the ligand L may also comprise a H donor atom. AnExamples of such a ligand is illustrated in Molecule XXVIII.

M-H  (XXVIII)

In an embodiment, leaving groups R described herein may include manydifferent suitable molecules. For example, the leaving groups mayinclude one or more of alkyls (C1-C10), alkenyls (internal or terminal),alkynyls (internal or terminal), aryls, or carbenes. The leaving groupsR may be linear, branched, or cyclic. In an embodiment, the leavinggroups R may also comprise Si, Ge, or Sn as the donor atom.

Examples of suitable alkyls are provided in Molecules XXIX and XXX.

Examples of suitable alkenyls are provided in Molecules XXXI-XXXIII

An example of a suitable alkynyl is provided in Molecule XXXIV.

Examples of suitable aryls are provided in Molecule XXXV and MoleculeXXXVI.

Examples of suitable carbenes are provided in Molecule XXXVII andMolecule XXXVIII.

Examples of leaving groups R that comprise Si, Ge, or Sn as the donoratom are shown in Molecules XXXIX-XLI, where X is Si, Ge, or Sn.

In an additional embodiment, the metal precursor may also includestannylene precursors. Molecule XLII is an example of a genericstannylene precursor. The ligand L may be any of the ligands L describedabove or generic amines (NR₂). The leaving group R may include any ofthe leaving groups R described above.

In yet another embodiment, the metal precursor may also be a genericmetallic precursor such as the one shown in Molecule XLIII. The R mayinclude any of the leaving groups R described above, and the metalcenter M may be any metal element such as, but not limited to, Sn, Hf,Zr, Co, Cr, Mn, Fe, Cu, Ni, Mo, W, Ta, Os, Re, Pd, Pt, Ti, V, In, Al,Sb, Bi, Te, As, Ge, Se, Cd, Ag, Pd, Au, Er, Yb, Pr, La, Na, or Mg. Suchgeneric metallic precursors may be used in combination with metalprecursors described above.

Referring now to FIG. 2, a flowchart illustrating a process 220 fordepositing a metal oxo photoresist on a substrate surface is provided,in accordance with an embodiment of the present disclosure. The process220 may be described as a CVD or a PE-CVD process. In a CVD process, thechemical reactions are driven thermally, whereas in a PE-CVD process thechemical reactions may be enhanced by the presence of a plasma. InPE-CVD processes a hydrocarbon may also be flown into the chamber duringplasma assisted deposition to incorporate more carbon into the film.When the plasma is on during the deposition, and if there arehydrocarbon molecules in the chamber, it may add more carbon to thefilm. A form of carbon could be M-C (M=metal). M-C (e.g., Sn—C) can besensitive to exposure. A hydrocarbon can be a carbon containingmolecule, such as, for example, CH₂═CH₂, acetylene, CH₄, propylene, etc.

In an embodiment, process 220 may begin with operation 221 whichcomprises providing a metal precursor vapor into a vacuum chambercontaining a substrate. The metal precursor vapor may comprise a metalprecursor such as those described in greater detail above. For example,the metal precursor may have the generic formula MR_(x)L_(y), where xand y are each between 0 and 6.

In an embodiment, the metal center M may comprise one or more of Sn, Hf,Zr, Co, Cr, Mn, Fe, Cu, Ni, Mo, W, Ta, Os, Re, Pd, Pt, Ti, V, In, Sb,Al, Bi, Te, As, Ge, Se, Cd, Ag, Pb, Au, Er, Yb, Pr, La, Na, and Mg. Theleaving group R may comprise one or more of alkyls, alkenyls (internalor terminal), alkynyls (internal or terminal), aryls, or carbenes. Theleaving group R may also comprise a Si donor atom, a Ge donor atom, or aSn donor atom. In an embodiment, the leaving group R may be linear,branched, or cyclic. In an embodiment, the ligands L may comprise pseudohalides, monodentate ligands with N donor atoms, monodentate orbidentate ligands with N, O, S, and/or P donor atoms, bidentate ligandswith one N donor atom and one O donor atom, a ligand with an N donoratom donating to more than one metal center M, or a hydrogen atom.

In other embodiments, the metal precursor may comprise a stannyleneprecursor or a generic metallic precursor such as shown in MoleculeXLIII. Additionally, it is to be appreciated that more than one metalprecursor vapor may be provided into the vacuum chamber. For example, afirst metal precursor may comprise Sn and a second metal precursor maycomprise Hf. In such embodiments, the resulting metal oxo photoresistmay comprise two or more different types of metal atoms. In anembodiment, the metal precursor vapor may be diluted by a carrier gas.The carrier gas may be an inert gas such as, Ar, N₂, or He.

In an embodiment, process 220 may continue with operation 222 whichcomprises providing an oxidant vapor into the vacuum chamber. In anembodiment, the oxidant vapor may comprise a carbon backbone withreactive groups on opposing ends of the carbon backbone. The reactivegroups initiate the reaction with the metal precursor that results inthe formation of a metal oxo photoresist on the substrate. In anembodiment, the oxidant vapor may comprise water or ethylene glycol. Inan embodiment, the oxidant vapor may be diluted by a carrier gas. Thecarrier gas may be an inert gas such as, Ar, N₂, or He.

In an embodiment, process 220 may continue with optional operation 223which comprises treating the metal oxo photoresist layer with a plasma.In an embodiment, the plasma treatment may include a plasma generatedfrom one or more inert gasses, such as Ar, N₂, He, etc. In anembodiment, the inert gas or gasses may also be mixed with one or moreoxygen containing gasses, such as O₂, CO₂, CO, NO, NO₂, H₂O, etc. In anembodiment, the vacuum chamber may be purged prior to operation 223. Thepurge may comprise a pulse of an inert gas such as Ar, N₂, He, etc.

In one embodiment, process 220 may be executed with operation 221 and222 being implemented at the same time. That is, providing a metalprecursor vapor to the vacuum chamber and providing an oxidant vapor tothe vacuum chamber may be done at the same time. After a metal oxophotoresist film with a desired thickness is formed, process 220 may behalted. In an embodiment, the optional plasma treatment operation 223may be executed after a metal oxo photoresist film with a desiredthickness is formed.

In other embodiments, process 220 may be executed in a pulsed manner.That is, a pulse of metal precursor vapor may be provided to the vacuumchamber followed by a pulse of the oxidant vapor. In an embodiment, acycle comprising a pulse of the metal precursor vapor and a pulse of theoxidant vapor may be repeated a plurality of times to provide a metaloxo photoresist film with a desired thickness. In an embodiment, theorder of the cycle may be switched. For example, the oxidant vapor maybe pulsed first and the metal precursor vapor may be pulsed second.

In an embodiment, a pulse duration of the metal precursor vapor may besubstantially similar to a pulse duration of the oxidant vapor. In otherembodiments, the pulse duration of the metal precursor vapor may bedifferent than the pulse duration of the oxidant vapor. In anembodiment, the pulse durations may be between 0 seconds and 1 minute.In a particular embodiment, the pulse durations may be between 1 secondand 5 seconds.

In an embodiment, each iteration of the cycle uses the same processinggasses. In other embodiments, the processing gasses may be changedbetween cycles. For example, a first cycle may utilize a first metalprecursor vapor, and a second cycle may utilize a second metal precursorvapor. Subsequent cycles may continue alternating between the firstmetal precursor vapor and the second metal precursor vapor. In anembodiment, multiple oxidant vapors may be alternated between cycles ina similar fashion.

In an embodiment, the optional plasma treatment of operation 223 may beexecuted after every cycle. That is, each cycle may comprise a pulse ofmetal precursor vapor, a pulse of oxidant vapor, and a plasma treatment.In an alternate embodiment, the optional plasma treatment of operation223 may be executed after a plurality of cycles. In yet anotherembodiment, the optional plasma treatment operation 223 may be executedafter the completion of all cycles (i.e., as a post treatment).

In an embodiment, process 220 may be a thermal process or a plasmaprocess. In the case of a thermal process, the reaction between themetal precursor vapor and the oxidant vapor may be driven thermally.Such an embodiment may be referred to as a CVD process. In the case of aplasma process, a plasma may be struck during one or both of operations221 and 222. In such instances, the presence of the plasma may enhancethe chemical reaction used to form the metal oxo photoresist. Such anembodiment may be referred to as a PE-CVD process. In an embodiment, anyplasma source may be used to form the plasma. For example, the plasmasource may include, but is not limited to, a capacitively coupled plasma(CCP) source, an inductively coupled plasma (ICP) source, a remoteplasma source, or a microwave plasma source.

In an embodiment, the vacuum chamber utilized in process 220 may be anysuitable chamber capable of providing a sub-atmospheric pressure. In anembodiment, the vacuum chamber may include temperature control featuresfor controlling chamber wall temperatures and/or for controlling atemperature of the substrate. In an embodiment, the vacuum chamber mayalso include features for providing a plasma within the chamber. A moredetailed description of a suitable vacuum chamber is provided below withrespect to FIG. 7.

In an embodiment, the substrate may be temperature controlled duringprocess 220. For example, the temperature of the substrate may bebetween approximately 0° C. and approximately 500° C. In a particularembodiment, the substrate may be held to a temperature between roomtemperature and 150° C.

Referring now to FIG. 3, a flowchart illustrating a process 340 fordepositing a metal oxo photoresist on a substrate surface is provided,in accordance with an additional embodiment of the present disclosure.The process 340 may be described as an ALD or a PE-ALD process. In anALD process, the chemical reactions are driven thermally, whereas in aPE-ALD process the chemical reactions may be enhanced by the presence ofa plasma. In PE-ALD processes a hydrocarbon may also be flown into thechamber during plasma assisted deposition to incorporate more carboninto the film. When the plasma is on during the deposition, and if thereare hydrocarbon molecules in the chamber, it may add more carbon to thefilm. A form of carbon could be M-C (M=metal). M-C (e.g., Sn—C) can besensitive to exposure. A hydrocarbon can be a carbon containingmolecule, such as, for example, CH₂═CH₂, acetylene, CH₄, propylene, etc.

In an embodiment, process 340 may begin with operation 341 whichcomprises providing a metal precursor vapor into a vacuum chambercontaining a substrate. In an embodiment, the metal precursor vapor maycomprise a molecule with one or more metal atoms. The metal precursorvapor may comprise a metal precursor such as those described in greaterdetail above. For example, the metal precursor may have the genericformula MR_(x)L_(y), where x and y are each between 0 and 6.

In an embodiment, the metal center M may comprise one or more of Sn, Hf,Zr, Co, Cr, Mn, Fe, Cu, Ni, Mo, W, Ta, Os, Re, Pd, Pt, Ti, V, In, Sb,Al, Bi, Te, As, Ge, Se, Cd, Ag, Pb, Au, Er, Yb, Pr, La, Na, and Mg. Theleaving group R may comprise one or more of alkyls, alkenyls (internalor terminal), alkynyls (internal or terminal), aryls, or carbenes. Theleaving group R may also comprise a Si donor atom, a Ge donor atom, or aSn donor atom. In an embodiment, the leaving group R may be linear,branched, or cyclic. In an embodiment, the ligands L may comprise pseudohalides, monodentate ligands with N donor atoms, monodentate orbidentate ligands with N, O, S, and/or P donor atoms, bidentate ligandswith one N donor atom and one O donor atom, a ligand with an N donoratom donating to more than one metal center M, or a hydrogen atom.

In other embodiments, the metal precursor may comprise a stannyleneprecursor or a generic metallic precursor such as shown in MoleculeXLIII. Additionally, it is to be appreciated that more than one metalprecursor vapor may be provided into the vacuum chamber. For example, afirst metal precursor may comprise Sn and a second metal precursor maycomprise Hf. In such embodiments, the resulting metal oxo photoresistmay comprise two or more different types of metal atoms. In anembodiment, the metal precursor vapor may be diluted by a carrier gas.The carrier gas may be an inert gas such as, Ar, N₂, or He.

In an embodiment, the metal precursor vapor absorbs to the surface ofthe substrate. In an embodiment, a monolayer of the metal precursor maybe provided substantially over a surface of the substrate. However, inother embodiments several layers of the metal precursor vapor may absorbto the surface of the substrate.

In an embodiment, process 340 may continue with operation 342 whichcomprises purging the vacuum chamber. In an embodiment, the purgingprocess removes residual metal precursor vapor and any byproducts fromthe vacuum chamber. The purging process may include a pulse of an inertgas such as, Ar, N₂, He, etc.

In an embodiment, process 340 may continue with operation 343 whichcomprises providing an oxidant vapor into the vacuum chamber. Theoxidant vapor reacts with the surface absorbed metal precursor to form ametal oxo photoresist layer over the surface of the substrate. Since themetal precursor is absorbed to the surface of the substrate, thereaction may be considered self-limiting. In an embodiment, the oxidantvapor may comprise a carbon backbone with reactive groups on opposingends of the carbon backbone. The reactive groups initiate the reactionwith the metal precursor that results in the formation of a metal oxophotoresist on the substrate. In an embodiment, the oxidant vapor maycomprise water or ethylene glycol. In an embodiment, the oxidant vapormay be diluted by a carrier gas. The carrier gas may be an inert gassuch as, Ar, N₂, or He.

In an embodiment, a pulse duration of the metal precursor vapor may besubstantially similar to a pulse duration of the oxidant vapor. In otherembodiments, the pulse duration of the metal precursor vapor may bedifferent than the pulse duration of the oxidant vapor. In anembodiment, the pulse durations may be between 0 seconds and 1 minute.In a particular embodiment, the pulse durations may be between 1 secondand 5 seconds.

In an embodiment, process 340 may continue with operation 344 whichcomprises purging the vacuum chamber. In an embodiment, the purgingprocess removes residual oxidant vapor and any byproducts from thevacuum chamber. The purging process may include a pulse of an inert gassuch as, Ar, N₂, He, etc.

In an embodiment, process 340 may continue with optional operation 345which comprises treating the metal oxo photoresist layer with a plasma.In an embodiment, the plasma treatment may include a plasma generatedfrom one or more inert gasses, such as Ar, N₂, He, etc. In anembodiment, the inert gas or gasses may also be mixed with one or moreoxygen containing gasses, such as O₂, CO₂, CO, NO, NO₂, H₂O, etc.

In an embodiment, processing operations 341-344 may define a cycle ofthe process 340. Embodiments may include repeating the cycle a pluralityof times in order to provide a metal oxo photoresist film with a desiredthickness. In an embodiment, the optional plasma treatment operation 345may be executed after each cycle. That is, each cycle may comprise apulse of metal precursor vapor, a purge, a pulse of oxidant vapor, apurge, and a plasma treatment. In other embodiments, the optional plasmatreatment operation 345 may be executed after a plurality of cycles. Inan additional embodiment, the optional plasma treatment operation 345may be executed after the completion of all cycles (i.e., as a posttreatment).

In an embodiment, each iteration of the cycle uses the same processinggasses. In other embodiments, the processing gasses may be changedbetween cycles. For example, a first cycle may utilize a first metalprecursor vapor, and a second cycle may utilize a second metal precursorvapor. Subsequent cycles may continue alternating between the firstmetal precursor vapor and the second metal precursor vapor. In anembodiment, multiple oxidant vapors may be alternated between cycles ina similar fashion.

In an embodiment, process 340 may be a thermal process or a plasmaprocess. In the case of a thermal process, the reaction between themetal precursor vapor and the oxidant vapor may be driven thermally.Such an embodiment may be referred to as an ALD process. In the case ofa plasma process, a plasma may be struck during one or both ofoperations 341 and 343. In such instances, the presence of the plasmamay enhance the chemical reaction used to form the metal oxophotoresist. Such an embodiment may be referred to as a PE-ALD process.In an embodiment, any plasma source may be used to form the plasma. Forexample, the plasma source may include, but is not limited to, a CCPsource, an ICP source, a remote plasma source, or a microwave plasmasource.

In an embodiment, the vacuum chamber utilized in process 340 may be anysuitable chamber capable of providing a sub-atmospheric pressure. In anembodiment, the vacuum chamber may include temperature control featuresfor controlling chamber wall temperatures and/or for controlling atemperature of the substrate. In an embodiment, the vacuum chamber mayalso include features for providing a plasma within the chamber. A moredetailed description of a suitable vacuum chamber is provided below withrespect to FIG. 7.

In an embodiment, the substrate may be temperature controlled duringprocess 340. For example, the temperature of the substrate may bebetween approximately 0° C. and approximately 500° C. In a particularembodiment, the substrate may be held to a temperature between roomtemperature and 150° C.

Referring now to FIG. 4, a cross-sectional illustration of a metal oxophotoresist layer 470 over a substrate 401 is shown, in accordance withan embodiment. In an embodiment, the metal oxo photoresist layer 470 maybe disposed over the substrate 401 using processes such as process 340or process 220. The metal oxo photoresist layer 470 may have asubstantially uniform composition through a thickness of the metal oxophotoresist layer. However, it is to be appreciated that the metal oxophotoresist may comprise more than one type of metal center M. Such anembodiment may be provided by flowing more than one type of metalprecursor into the vacuum chamber at the same time or in alternatingpulses.

It is to be appreciated that embodiments are not limited tosubstantially uniform metal oxo photoresist layers. For example, thecomposition of the metal oxo photoresist layer may be modulated througha thickness of the metal oxo photoresist layer. For example, the metalcenter may be changed, the percentage of metal may be changed, or thecarbon concentration may be changed, among other variations.

Changes to the composition of the metal oxo photoresist layer in thethickness direction is enabled by the vacuum deposition processes usedto form the metal oxo photoresist. For example, the metal precursorvapor or the oxidant vapor may be changed (e.g., different molecules maybe used, different flow rates of the vapors may be used, etc.) atdifferent points in the deposition of the metal oxo photoresist. This isa significant improvement over existing wet based spin on processes thatare limited to having a substantially uniform material compositionthrough the thickness of the photoresist layer.

As such, embodiments disclosed herein enable enhanced tunability inorder to optimize the metal oxo photoresist layer for variousapplications. For example, the first few nanometers (e.g., the first 10nm or less) of the metal oxo photoresist layer over the substrate mayhave a different composition than the rest of the film. This may allowthe remainder of the metal oxo photoresist is optimized for dose whilethe bottom portion is tuned to have improved adhesion, sensitivity toEUV photons, or sensitivity to develop chemistry in order to improvepost lithography pattern control (e.g., scumming), as well asdefectivity and resist collapse/lift off. In other embodiments, acomposition gradient may be provided through the thickness of the metaloxo photoresist. Grading the material composition may be used to controlthe exposure latitude curve of the photoresist. This allows for controlof the developed profile of the photoresist and/or can be used toprovide OPC. The gradation may also be optimized for pattern type. Forexample, pillars may need improved adhesion, whereas line/space patternsmay allow for lower adhesion while tuning for improvements in dose.

Referring now to FIG. 5, a flowchart illustrating a process 550 fordepositing a metal oxo photoresist on a substrate surface is provided,in accordance with an additional embodiment of the present disclosure.In process 550, the material composition of the metal oxo photoresist isnon-uniform through the thickness of the metal oxo photoresist. Process550 may begin with operation 551, which includes forming a first metaloxo film on a substrate with a first vapor phase process. In anembodiment, the first vapor phase process may include a first metalprecursor vapor and a first oxidant vapor. In an embodiment, the firstvapor phase process may comprise a CVD or a PE-CVD process similar tothe processes 220 described above. In an additional embodiment, thefirst vapor phase process may comprise an ALD or a PE-ALD processsimilar to the process 340 described above. The first metal precursorvapor may include any of the metal precursor vapors described in greaterdetail above.

In an embodiment, process 550 may continue with operation 552, whichincludes forming a second metal oxo film over the first metal oxo filmwith a second vapor phase process including a second metal precursorvapor and a second oxidant vapor. In an embodiment, the second vaporphase process may comprise a CVD or a PE-CVD process similar to theprocesses 220 described above. In an additional embodiment, the secondvapor phase process may comprise an ALD or a PE-ALD process similar tothe process 340 described above. In an embodiment, the second metalprecursor vapor and/or the second oxidant vapor may be different thanthe first metal precursor vapor and the first oxidant vapor.Accordingly, the second metal oxo film may have a different compositionthan the first metal oxo film.

In some embodiments, only two different metal oxo film layers areprovided. An example of such an embodiment is shown in FIG. 6A. Asshown, a photoresist layer comprising a first metal oxo film 671 and asecond metal oxo film 672 is disposed over a substrate 601. In anembodiment, the first metal oxo film 671 is an interface layer thatprovides an improved adhesion to the substrate 601. The first metal oxofilm 671 may have a thickness that is approximately 10 nm or less.

In other embodiments, the photoresist layer may comprise a plurality ofdifferent metal oxo film layers. An example, of such an embodiment isshown in FIG. 6B. As shown, the photoresist layer comprises a pluralityof different metal oxo film layers 671-678 with different compositions.Such an embodiment may be formed using process 550 with the inclusion ofadditional vapor phase processes for each layer. In the illustratedembodiment, each of the layers 671-678 are substantially uniform inthickness. However, it is to be appreciated that embodiments may includemetal oxo film layers with non-uniform thicknesses.

In an embodiment, process 550 may further comprise an optional plasmatreatment of the metal oxo film (or films). In an embodiment, the plasmatreatment may be implemented after the deposition of both the firstmetal oxo film and the second metal oxo film. Alternatively, the plasmatreatment may be implemented after the deposition of each metal oxofilm. That is, the first metal oxo film may be deposited and followed bya plasma treatment before the deposition of the second metal oxo film.In an embodiment, the plasma treatment may include a plasma generatedfrom one or more inert gasses, such as Ar, N₂, He, etc. In anembodiment, the inert gas or gasses may also be mixed with one or moreoxygen containing gasses, such as O₂, CO₂, CO, NO, NO₂, H₂O, etc.

Providing metal oxo photoresist films using vapor phase processes suchas described in the embodiments above provides significant advantagesover wet chemistry methods. One such advantage is the elimination of wetbyproducts. With a vapor phase process, liquid waste is eliminated andbyproduct removal is simplified. Additionally, vapor phase processesprovide a more uniform photoresist layer. Uniformity in this sense mayrefer to thickness uniformity across the wafer and/or uniformity of thedistribution of metal components of the metal oxo film. Particularly,CVD, PE-CVD, ALD, and PE-ALD processes have been shown to provideexcellent thickness uniformity and constituent uniformity.

Additionally, the use of vapor phase processes provides the ability tofine-tune the percentage of metal in the photoresist and the compositionof the metal in the photoresist. The percentage of the metal may bemodified by increasing/decreasing the flow rate of the metal precursorinto the vacuum chamber and/or by modifying the pulse lengths of themetal precursor/oxidant. The use of a vapor phase process also allowsfor the inclusion of multiple different metals into the metal oxo film.For example, a single pulse flowing two different metal precursors maybe used, or alternating pulses of two different metal precursors may beused. The use of a vapor phase process also allows for the formation ofmetal oxo films with different material compositions in order to tunethe photoresist for a desired application.

Furthermore, it has been shown that metal oxo photoresists that areformed using vapor phase processes are more resistant to thicknessreduction after exposure. It is believed, without being tied to aparticular mechanism, that the resistance to thickness reduction isattributable, at least in part, to the reduction of carbon loss uponexposure.

FIG. 7 is a schematic of a vacuum chamber configured to perform a vaporphase deposition of a metal oxo photoresist, in accordance with anembodiment of the present disclosure. Vacuum chamber 700 includes agrounded chamber 705. A substrate 710 is loaded through an opening 715and clamped to a temperature controlled chuck 720.

Process gases, are supplied from gas sources 744 through respective massflow controllers 749 to the interior of the chamber 705. In certainembodiments, a gas distribution plate 735 provides for distribution ofprocess gases 744, such as a metal precursor, an oxidant, and an inertgas. Chamber 705 is evacuated via an exhaust pump 755.

When RF power is applied during processing of a substrate 710, a plasmais formed in a chamber processing region over substrate 710. Bias powerRF generator 725 is coupled to the temperature controlled chuck 720.Bias power RF generator 725 provides bias power, if desired, to energizethe plasma. Bias power RF generator 725 may have a low frequency betweenabout 2 MHz to 60 MHz for example, and in a particular embodiment, is inthe 13.56 MHz band. In certain embodiments, the vacuum chamber 700includes a third bias power RF generator 726 at a frequency at about the2 MHz band which is connected to the same RF match 727 as bias power RFgenerator 725. Source power RF generator 730 is coupled through a match(not depicted) to a plasma generating element (e.g., gas distributionplate 735) to provide a source power to energize the plasma. Source RFgenerator 730 may have a frequency between 100 and 180 MHz, for example,and in a particular embodiment, is in the 162 MHz band. Becausesubstrate diameters have progressed over time, from 150 mm, 200 mm, 300mm, etc., it is common in the art to normalize the source and bias powerof a plasma etch system to the substrate area.

The vacuum chamber 700 is controlled by controller 770. The controller770 may comprise a CPU 772, a memory 773, and an I/O interface 774. TheCPU 772 may execute processing operations within the vacuum chamber 700in accordance with instructions stored in the memory 773. For example,one or more processes such as processes 220, 340, and 550 describedabove may be executed in the vacuum chamber by the controller 770.

FIG. 8 illustrates a diagrammatic representation of a machine in theexemplary form of a computer system 800 within which a set ofinstructions, for causing the machine to perform any one or more of themethodologies described herein, may be executed. In alternativeembodiments, the machine may be connected (e.g., networked) to othermachines in a Local Area Network (LAN), an intranet, an extranet, or theInternet. The machine may operate in the capacity of a server or aclient machine in a client-server network environment, or as a peermachine in a peer-to-peer (or distributed) network environment. Themachine may be a personal computer (PC), a tablet PC, a set-top box(STB), a Personal Digital Assistant (PDA), a cellular telephone, a webappliance, a server, a network router, switch or bridge, or any machinecapable of executing a set of instructions (sequential or otherwise)that specify actions to be taken by that machine. Further, while only asingle machine is illustrated, the term “machine” shall also be taken toinclude any collection of machines (e.g., computers) that individuallyor jointly execute a set (or multiple sets) of instructions to performany one or more of the methodologies described herein.

The exemplary computer system 800 includes a processor 802, a mainmemory 804 (e.g., read-only memory (ROM), flash memory, dynamic randomaccess memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM(RDRAM), etc.), a static memory 806 (e.g., flash memory, static randomaccess memory (SRAM), MRAM, etc.), and a secondary memory 818 (e.g., adata storage device), which communicate with each other via a bus 830.

Processor 802 represents one or more general-purpose processing devicessuch as a microprocessor, central processing unit, or the like. Moreparticularly, the processor 802 may be a complex instruction setcomputing (CISC) microprocessor, reduced instruction set computing(RISC) microprocessor, very long instruction word (VLIW) microprocessor,processor implementing other instruction sets, or processorsimplementing a combination of instruction sets. Processor 802 may alsobe one or more special-purpose processing devices such as an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA), a digital signal processor (DSP), network processor, or thelike. Processor 802 is configured to execute the processing logic 826for performing the operations described herein.

The computer system 800 may further include a network interface device808. The computer system 800 also may include a video display unit 810(e.g., a liquid crystal display (LCD), a light emitting diode display(LED), or a cathode ray tube (CRT)), an alphanumeric input device 812(e.g., a keyboard), a cursor control device 814 (e.g., a mouse), and asignal generation device 816 (e.g., a speaker).

The secondary memory 818 may include a machine-accessible storage medium(or more specifically a computer-readable storage medium) 832 on whichis stored one or more sets of instructions (e.g., software 822)embodying any one or more of the methodologies or functions describedherein. The software 822 may also reside, completely or at leastpartially, within the main memory 804 and/or within the processor 802during execution thereof by the computer system 800, the main memory 804and the processor 802 also constituting machine-readable storage media.The software 822 may further be transmitted or received over a network820 via the network interface device 808.

While the machine-accessible storage medium 832 is shown in an exemplaryembodiment to be a single medium, the term “machine-readable storagemedium” should be taken to include a single medium or multiple media(e.g., a centralized or distributed database, and/or associated cachesand servers) that store the one or more sets of instructions. The term“machine-readable storage medium” shall also be taken to include anymedium that is capable of storing or encoding a set of instructions forexecution by the machine and that cause the machine to perform any oneor more of the methodologies of the present disclosure. The term“machine-readable storage medium” shall accordingly be taken to include,but not be limited to, solid-state memories, and optical and magneticmedia.

In accordance with an embodiment of the present disclosure, amachine-accessible storage medium has instructions stored thereon whichcause a data processing system to perform a method of depositing a metaloxo photoresist on a substrate. The method includes vaporizing a metalprecursor into a vacuum chamber and vaporizing an oxidant into thevacuum chamber. The metal precursor and the oxidant may be sequentiallyprovided into the vacuum chamber or supplied to the vacuum chamber atthe same time. The reaction between the metal precursor and the oxidantresult in the formation of the metal oxo photoresist on the substrate.The metal oxo photoresist may be treated with a plasma treatment in someembodiments.

Thus, methods for forming a metal oxo photoresist using vapor phaseprocesses have been disclosed.

What is claimed is:
 1. A method of forming a photoresist layer over asubstrate, comprising: forming a first metal oxo film on the substratewith a first vapor phase process including a first metal precursor vaporand a first oxidant vapor; and forming a second metal oxo film over thefirst metal oxo film with a second vapor phase process including asecond metal precursor vapor and a second oxidant vapor.
 2. The methodof claim 1, wherein a material composition of the first metal oxo filmis different than a material composition of the second metal oxo film.3. The method of claim 1, wherein a thickness of the first metal oxofilm is approximately 5 nm or less.
 4. The method of claim 3, whereinthe first metal precursor vapor is different than the second metalprecursor vapor, and/or the first oxidant vapor is different than thesecond oxidant vapor.
 5. The method of claim 1, wherein the first vaporphase process and the second vapor phase process are chemical vapordeposition (CVD) processes, plasma enhanced CVD (PE-CVD) processes,atomic layer deposition (ALD) processes, or plasma enhanced ALD (PE-ALD)processes.
 6. The method of claim 1, wherein a sensitivity of the firstmetal oxo film is less than a sensitivity of the second metal oxo film.7. The method of claim 1, wherein an adhesion strength of the firstmetal oxo film is greater than an adhesion strength of the second metaloxo film.
 8. The method of claim 1, further comprising: forming aplurality of additional metal oxo films over the second metal oxo film,wherein the first metal oxo film, the second metal oxo film, and theplurality of additional metal oxo films provide a compositionalgradient.
 9. A method of forming a photoresist layer over a substrate ina vacuum chamber, comprising: providing a metal precursor vapor into thevacuum chamber, wherein the metal precursor has a generic formulaMR_(x)L_(y), wherein M is a metal, R is a leaving group, L is a ligand,x is between 0 and 6, and y is between 0 and 6; and providing an oxidantvapor into the vacuum chamber, wherein a reaction between the metalprecursor vapor and the oxidant vapor results in the formation of thephotoresist layer on a surface of the substrate, wherein the photoresistlayer is a metal oxo containing material.
 10. The method of claim 9,further comprising: striking a plasma in the vacuum chamber during oneor both of providing a metal precursor vapor into the vacuum chamber andproviding an oxidant vapor into the vacuum chamber.
 11. The method ofclaim 9, further comprising: treating the photoresist layer with aplasma.
 12. The method of claim 9, wherein the ligand comprises a pseudohalide, a monodentate ligand comprising a nitrogen donor atom, abidentate ligand comprising one or more of a nitrogen donor atom, anoxygen donor atom, a sulfur donor atom, and a phosphorous donor atom, aligand with a nitrogen donor atom donating to more than one metalcenters, or a hydrogen ligand.
 13. The method of claim 9, wherein theleaving group comprises one or more of an alkyl, an alkenyl, an alkynyl,an aryl, a carbene, or a leaving group comprising silicon, germanium, ortin as the donor atom.
 14. A method of forming a photoresist layer overa substrate in a vacuum chamber, comprising: initiating a depositioncycle, wherein the deposition cycle comprises: providing a metalprecursor vapor into the vacuum chamber, wherein the metal precursor hasa generic formula MR_(x)L_(y), wherein M is a metal, R is a leavinggroup, L is a ligand, x is between 0 and 6, and y is between 0 and 6,and wherein the metal precursor vapor absorbs to a surface over thesubstrate; purging the vacuum chamber; providing an oxidant vapor intothe vacuum chamber, wherein a reaction between the metal precursorabsorbed to the surface over the substrate and the oxidant vapor resultsin the formation of the photoresist layer over the surface of thesubstrate, wherein the photoresist layer is a metal oxo containingmaterial; and purging the vacuum chamber.
 15. The method of claim 14,further comprising: repeating the deposition cycle a plurality of times.16. The method of claim 14, further comprising: striking a plasma in thevacuum chamber during the deposition cycle.
 17. The method of claim 14,wherein the ligand comprises a pseudo halide, a monodentate ligandcomprising a nitrogen donor atom, a bidentate ligand comprising one ormore of a nitrogen donor atom, an oxygen donor atom, a sulfur donoratom, and a phosphorous donor atom, a ligand with a nitrogen donor atomdonating to more than one metal centers, or a hydrogen ligand.
 18. Themethod of claim 14, wherein the leaving group comprises one or more ofan alkyl, an alkenyl, an alkynyl, an aryl, a carbene, or a leaving groupcomprising silicon, germanium, or tin as the donor atom.
 19. The methodof claim 14, wherein the deposition cycle further comprises: treatingthe photoresist layer with a plasma.
 20. The method of claim 19, furthercomprising: treating the photoresist layer with a plasma after repeatingthe deposition cycle the plurality of times.